Benaderet AD, Burton AM, Clifton-Bligh R, Ashraf AP. Primary hyperparathyroidism with low intact PTH levels in a 14-year-old girl.
J Clin Endocrinol Metab 2011;
96:2325-9. [PMID:
21593105 PMCID:
PMC3206518 DOI:
10.1210/jc.2011-0247]
[Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT
Primary hyperparathyroidism (PHPT) is usually associated with hypercalcemia and inappropriately elevated serum PTH.
OBJECTIVE
Our objective was to identify the reason(s) for a low serum intact PTH in a child with PHPT.
SUBJECT AND METHODS
A 14-yr-old Caucasian girl presented with pancreatitis, nephrolithiasis, hypercalcemia ranging from 13.2 to 17.5 mg/dl, and a low serum intact PTH. She had an ultrasound and technetium-99m-sestamibi scintigraphy confirming the presence of a parathyroid adenoma.
RESULTS
The preoperative serum intact PTH assays performed at Quest Diagnostics, Nichols Institute, were low even after serial dilutions, whereas the intraoperative turbo PTH assay was elevated at 3618 pg/ml. C-terminal and cyclase-activating PTH assays for PTH were also elevated. PTH gene sequence analysis performed from DNA extracted both from the parathyroid adenoma and the patient's peripheral blood leukocytes was negative for a mutation in the PTH gene sequence.
CONCLUSIONS
The contrasting values on the intact PTH assay and the turbo PTH assay suggest that the adenoma was producing an aberrant PTH molecule that was not detected by the routine intact PTH assay. Because there was no change in PTH gene sequence, this could be indicative of a posttranslational change in the PTH molecule that would not be recognized solely by DNA sequencing. Therefore, a low or normal PTH measurement against the backdrop of clinical and biochemical hyperparathyroidism needs measurement with a variety of assays.
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